At around 6am Swiss time last Wednesday, Sepp Blatter would have almost certainly arrived at his office at Fifa's headquarters - as he usually does - logged into his computer and switched on the news.

The most powerful man in football would have been oblivious to the fact that a tsunami was about to be unleashed that would end, within a week, one of the most controversial reigns in sporting history.

It was at that moment that Swiss police, acting on behalf of the FBI, swooped on the luxury Baur au Lac hotel, the long-time Zurich residence of Fifa's ruling executive committee, and seized several officials from their beds, including two of Blatter's vice-presidents.

Each had been arrested and indicted on fraud and bribery charges dating back almost a quarter of a century involving alleged sums totalling £100m.

Within hours, Fifa HQ was also raided as part of a separate criminal investigation into the award of the 2018 and 2022 World Cups.

Football's world governing body was in meltdown. Its director of communications hastily convened a press conference in which he tried to spin events into "a good day for Fifa", brushed aside calls for Blatter to resign and said of his boss's reaction: "He's not dancing in his office."

If Blatter did not appreciate the seriousness of what was unfolding, he was soon to be disabused by the United States Attorney General, Loretta Lynch, who detailed the full charges against nine top Fifa officials and five marketing executives.

Allegation followed allegation, the most sensational arguably the claim that South Africa had paid a bribe of $10m in order to secure the 2010 World Cup.

"The indictment alleges corruption that is rampant, systemic and deep-rooted," Lynch said.

She was followed by the FBI director, James Comey, and the IRS chief of criminal investigation, Richard Weber, who summarised the 164-page indictment - based partly on secret recordings made by the supergrass former Fifa executive Chuck Blazer - as the "World Cup of fraud".

Statements flowed calling for Blatter to withdraw from or postpone the presidential election two days later, which Uefa threatened to boycott.

Sponsors also voiced concern, with Visa threatening to walk away, but the 79-year-old stood defiant.

Not even the pleas of his one-time ally and now bitter rival Michel Platini during an emergency meeting the following morning could move the Swiss.

There was talk of World Cup boycotts, setting up rival tournaments and even forcing a vote of no confidence in Blatter. Platini announced a special meeting of Uefa's own executive committee ahead of the Champions League final, at which he said it would be "open to all options".

Opening Fifa's annual congress at the Hallenstadion that evening, Blatter ignored the boycott threat by vowing finally to clean up the governing body.

He admitted the damning criminal charges faced by several of his most senior lieutenants had brought "shame and humiliation" to Fifa and warned there could be more to come.

However, he snubbed more calls for him to resign by insisting that he could not be expected to take responsibility for the actions of those whose alleged bribery scam had dragged Fifa's name "through the mud".

Chief among them is his former vice-president Jack Warner, who was arrested in Trinidad only to be freed on bail with exhaustion. Despite being carted away in an ambulance, the shameless Warner re-emerged - dancing - at a political rally in which he said of Blatter: "Why ain't he charged?"

The Swiss's own campaign of denial continued when congress began in earnest the following morning, saying: "You can't ask people to behave ethically just like that."

He launched the first of a series of attacks on the FBI investigation and British media reporting of Fifa corruption, insinuating it was motivated by the US and England losing out on hosting one of the next two World Cup finals.

This played perfectly with his core voters from Africa and Asia, as did much of went on at congress, which was little more than a campaign advert for Blatter's re-election.

When he duly beat Prince Ali bin Al-Hussein by 133 votes to 73 - not quite the required majority but enough for his opponent to concede - he cavorted around the stage like a giddy teenager.

"For the next four years, I will be in command of this boat called Fifa we will bring back, we will bring it back ashore," he said to applause in a speech which ended with him chanting: "Let's go Fifa. Let's go Fifa."

Finally granting a press conference three days after the crisis began, Blatter himself declared that he had "no concerns" over suggestions he could face charges himself.

"Arrested for what?" he snapped, insisting he was "definitely" not the high-ranking official accused of authorising the alleged $10m bribe paid by South Africa to Warner and Blazer.

Blatter had already granted an interview to his local television network in which he said: "Why would I step down? That would mean I recognise that I did wrong."

If Blatter was hoping the "storm" would recede, he was mistaken as the internal revolt against him intensified.

Although each day had also brought a new arrest somewhere in the world, the final straw appeared to be the revelation that two of Blatter's closest colleagues during his 17-year presidency had been linked directly to the alleged 2010 World Cup bribe.

Fifa admitted that the long-serving vice-president Julio Grondona, who died last year, authorised the payment, while a letter emerged addressed to secretary general Jerome Valcke informing him of the transaction. The governing body insisted it was legitimate development money but did not respond to queries about who knew about it.

Amid speculation that Valcke would make a convenient scapegoat - and ahead of the publication of Blazer's FBI evidence - Blatter did what many thought unthinkable and finally took responsibility for his 17-year watch.

Why go now?

Why did Blatter resign only four days after being re-elected?

It was a dramatic change of position from a man who had not shown any self-doubt in 17 years as Fifa president. His response to corruption investigations into Fifa being conducted in the USA and Switzerland had until yesterday been indignant.

So what changed?

He said it had become clear to him that while he had a mandate from Fifa members, he did not have a mandate from the wider footballing world.

Being unpopular with the public had not bothered him before?

Yes - many suspect the only reason he has now resigned is that he feared the FBI or Swiss corruption allegations were going to lead to his office.

How likely is that to happen?

If the investigations prove the World Cup bidding processes were corrupt, Blatter's position as the official who oversaw them would have been untenable.

And the FBI probe?

FA chairman Greg Dyke, said Blatter's resignation showed there must be a "smoking gun" in terms of evidence against him, and reports in America said Blatter was definitely under FBI investigation. Blatter may have concerns that former allies who have been arrested might cooperate with investigators in order to secure more lenient treatment. Fifa general secretary Jerome Valcke was drawn into corruption allegations yesterday, and that may have spooked Blatter.

Is that the last we'll see of Blatter?

No. He said he would carry on in the role until the outcome of the new election. One intriguing question is whether he will travel to the women's World Cup in Canada. An ESPN documentary last month claimed he had not been to north America for four years because of the FBI investigation.

Who will take over?

Prince Ali of Jordan, who was defeated last week, could stand again. Michel Platini may also stand, but would have to overcome strong anti-European sentiment which Blatter has fostered in Fifa. Bahrain's Sheikh Salman and Kuwait's Shekih Jaber Al-Sabah are both powerful, wealthy figures who would command support.